Pritchard 2003

Methods	Double‐blind, randomised, parallel‐group trial with 2:1 IFNb‐1a to placebo ratio
Participants	19 people with GBS fulfilling Asbury 1990 criteria within 14 days from the onset of symptoms and having Hughes 1978 disability grade > 2
Interventions	IFNb‐1a (Rebif) by subcutaneous injection 3 times a week starting with 22 μg per injection for the first week and continuing with 44 μg for subsequent weeks until a total of 24 weeks (n = 13) or placebo (n = 6). Participants stopped treatment upon reaching grade 2
Outcomes	Improvement in disability grade 4 weeks after randomisation, improvement by 1 or more disability grades 4 weeks after randomisation, time from randomisation to recovery of unaided walking Serious adverse events (defined as "fatal, life threatening, requiring or prolonging hospitalization, severely or permanently disabling, a new malignancy, or a known or suspected overdose")
Funding source	Serono International provided financial support and supplied the drug and placebo
Declarations of interest	The trial authors declared receipt of honoraria or travel grants and departmental research grants from Serono International
Notes	Participants in both groups received IVIg. This was a safety and tolerability study. There was no unexpected interaction with IVIg. A significant effect on efficacy outcomes was not expected because of the small sample size
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Each centre was given study drug in a computer‐generated (information from the authors) random sequence by the trial statistician balanced to achieve a 2:1 ratio of IFNb‐1a to placebo
Allocation concealment (selection bias)	Low risk	Each centre was given study drug in random sequence balanced to achieve a 2:1 ratio of IFNb‐1a to placebo and concealed until all outcome measures, including attribution of causality of adverse events, had been collected
Blinding (performance bias and detection bias) All outcomes	High risk	No attempt was made to mask skin lesions from assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete case analysis reported
Selective reporting (reporting bias)	Low risk	Complete case analysis of all outcomes reported
Other bias	Low risk	None detected